The present invention relates to a vehicle speed control apparatus of an automobile and more particularly relates to an apparatus for automatically maintaining the vehicle speed at a desired speed without driver operation of the accelerator pedal.
A conventional vehicle speed control apparatus consists of a storing device which stores the actual running speed of an automobile at the time when a set switch is operated, a comparator which compares the actual running speed with the stored running speed, and a speed adjustor which adjusts the opening degree of a throttle valve to maintain the running speed of the automobile at the stored running speed in other words, at the desired running speed.
However, the conventional vehicle speed control apparatus has no increase operation mechanism for increasing the stored running speed either continuously or in fairly large increments. Therefore, according to the prior art, in order to increase the stored running speed, it is necessary to discontinue the operation of the automatic vehicle speed control and to increase the actual running speed of the vehicle by depressing the accelerator pedal. The set switch is then operated causing the automatic vehicle control operation to resume. Therefore, according to the prior art, this very complicated procedure is necessary to increase the stored running speed.
It is, therefore, an object of the present invention to provide a vehicle speed control apparatus which is capable of increasing the stored running speed without complicated procedures.
Another object of the present invention is to provide a vehicle speed control apparatus which is capable of preventing a setting operation from being carried out when an increase switch for increasing the stored running speed malfunctions.
A further object of the present invention is to provide a vehicle speed control apparatus which is capable of correctly performing both a resuming operation for resuming the vehicle speed control operation to maintain the vehicle speed at the stored running speed and an increasing operation for increasing the stored running speed by a single operation switch.